2.5 Cell Recognition and the Immune System

• Receptors have an extracellular domain that binds to ligands and an intracellular domain that interacts with cellular machinery.

  True
• Cell surface receptors facilitate cell signaling by detecting external stimuli like hormones, neurotransmitters, and cytokines.
• Ion channel receptors propagate signals by activating intracellular G proteins.

  False
• What is one function of cell surface receptors in cell signaling?

  Detecting external stimuli
• What is the purpose of antigen-antibody binding in the immune system?

  Neutralizing pathogens
• Match the type of antigen-antibody binding with its purpose:

  Neutralization ↔️ Prevents pathogen entry

  Opsonization ↔️ Enhances phagocytosis

  Agglutination ↔️ Facilitates removal

  Complement fixation ↔️ Destroys pathogens
• What is the first line of defense against pathogens in the immune system?

  Innate immunity
• What type of immune response involves B cells and T cells?

  Adaptive immunity
• Arrange the following components of the immune system in order from non-specific to antigen-specific:

  1️⃣ Innate immunity

  2️⃣ Adaptive immunity
• Receptors have a transmembrane domain that anchors them to the cell membrane.
• What are cell surface receptors composed of?

  Proteins or glycoproteins
• Glycoproteins contain carbohydrate chains attached to their protein structure

  True
• G-protein coupled receptors (GPCRs) activate intracellular G proteins
• What type of receptors open ion channels for ion flow?

  Ion channel receptors
• Cell surface receptors are located on the plasma membrane of cells.
• What type of structures are common in cell surface receptors?

  Proteins and glycoproteins
• Match the receptor type with its signaling mechanism:

  G-protein coupled receptors (GPCRs) ↔️ Activates intracellular G proteins

  Receptor tyrosine kinases (RTKs) ↔️ Dimerization and phosphorylation

  Ion channel receptors ↔️ Opens ion channels for ion flow
• Arrange the domains of a cell surface receptor in order from outside to inside the cell:

  1️⃣ Extracellular domain

  2️⃣ Transmembrane domain

  3️⃣ Intracellular domain
• Cell recognition enabled by receptors allows cells to interact and communicate.


  True
• Antigen-antibody binding involves non-covalent bonds such as hydrogen bonds, van der Waals forces, and hydrophobic interactions.
• Antigen-antibody binding ensures targeted elimination of antigens.

  True
• Examples of innate immunity include physical barriers, phagocytic cells, and inflammatory responses.
• Innate immunity develops immunological memory.

  False
• What type of molecules are cell surface receptors made of?

  Proteins or glycoproteins
• Cell surface receptors facilitate cell recognition by binding to specific signaling molecules.

  True
• Cell surface receptors have an extracellular domain that binds to ligands
• What do cell surface receptors detect and respond to?

  External stimuli
• Receptor tyrosine kinases (RTKs) undergo dimerization and phosphorylation upon ligand binding


  True
• Match the receptor type with its signaling mechanism:

  GPCRs ↔️ Activates G proteins

  RTKs ↔️ Dimerization and phosphorylation

  Ion channel receptors ↔️ Opens ion channels
• Antibody specificity ensures it binds to only one type of antigen

  True
• Neutralization involves antibodies binding to pathogens to prevent their entry
• Which type of antigen-antibody binding clumps antigens together for easier removal?

  Agglutination
• What are the two main components of the immune system?

  Innate and adaptive immunity
• Which type of immunity develops immunological memory?

  Adaptive immunity
• What type of adaptive immunity involves B cells producing antibodies?

  Humoral immunity
• What are the two main types of adaptive immunity?

  Humoral and cell-mediated
• What do antibodies do in humoral immunity?

  Bind to and neutralize pathogens
• In cell-mediated immunity, T cells release cytokines
• What is the role of MHC proteins in antigen presentation?

  Present peptides to T cells
• MHC II proteins present antigens from extracellular pathogens.